feat: Phase 4 - CI/CD, Static Analysis, Browser Tests

- Add GitHub Actions CI workflow (.github/workflows/ci.yml)
  - Laravel Pint code style check
  - PHPStan static analysis (level 5)
  - Test suite with parallel execution
  - Dusk browser tests (disabled by default)
- Add phpstan.neon config (level 5, ignores User notifications methods)
- Add Dusk browser tests (ProjectWorkflowTest)
- Install laravel/dusk + chromedriver

Tests: 101 passing (319 assertions)

tests/Browser/Pages/Page.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Tests\Browser\Pages;
+
+use Laravel\Dusk\Page as BasePage;
+
+abstract class Page extends BasePage
+{
+    /**
+     * Get the global element shortcuts for the site.
+     *
+     * @return array<string, string>
+     */
+    public static function siteElements(): array
+    {
+        return [
+            '@element' => '#selector',
+        ];
+    }
+}